Dampening devices for shock absorbers and the like



J 1949- P. B. OBERSTADT v 2,459,537

DAMPENIIG DEVICES FOR SHOCK ABSORBERS AND THE LIKE Filed May 27, 1946 INVENTOR. PETER B.OBERSTADT Jig-5 Owl-303M ATTORNEYS Patented Jan. 18, 1949 UNITED! STATES OFFICE DAMPENING DEVICES FOR SHOGK ABSORBERS ANDTHEICLIKEL Peter B. Oberstaldt, Wickliife; Ohio Application May 27, 1946, Serial No'...6Z2.,550,

11 Claims; (010188-129 Thepresent. invention relates to improvements in. a Idevice for. dampening or cushioning the movement or movements of relatively movable parts,. such device. being commonly termed a shock absorber when. used for example for dampening the movements between the sprung mass and the unsprung mass of" a vehicle.

It. is one. object of this invention. to provide a dampening device which is simple in structure and eflicient in operation.

It is another object of this invention to provide a dampening device which offers greater resistance and thus greater dampening effect to movement of. the parts with which it is associated in one direction of their relative movement than in W the other. direction.

Another object is to provide a dampening device in the general-form of a piston and cylinder type, hydraulic shock absorberbut'without the attendant problems of providing leak' proof packings, gaskets or the like.

Another object is to provide a dampening device wherein the dampening effect can readily be adjusted over a wide range to suit particular applications.

Additional objects and advantages of the invention. will become apparentasthe following description proceeds. I

To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter; fullydescribed and particularly pointed out inythe claims, the-following description and. the annexed drawingsetting forth in detail; certain illustrative embodiments of the invention, these being-indicative; however; of but a few of the various ways'in which the=principle-of the invention maybe employed:

In the drawing:

Fig. 1. is. a longitudinal-central crosssection view of. one form" of dampeningdevice showing such device in .a static or-neutra1- position;

Fig. 2 is a transversecross section view or the device illustrated in-Fig. l taken along 1ine Z*2 of Fig. 1;.

Fig. .3 is a fragmentary" longitudinal central cross section viewof a. modified formofdampening device;

Fig, 4 is a fragmentary longitudinal: central 1 cross. section. view of. still, another modified form of dampening device;

. Fig. 5 is. a. transverse cross section view fgthe modified form of, device illustrated in Fig: 4 taken along line.5-5' of Fig. 4;

Fig 6 is a fragmentary, longitudinal .crossisection view ofstill another modifiedform ofd'amp- 2;. another form of dampening device taken along a line corresponding to line 2'2of Fig. 1.

Referring now to the drawing and first to Figs. 1 and 2', there is shown thereinrelatively movable telescoped elements I and 2, each of which may be provi'd'edtwith. an" eve '3 for connection to the. parts whose. movement it is desired to dampen, as: for example the unsprung mass (the axle) and the sprung mass (the frame) of a vehicle. Element I- is preferably in the form of a tube orhollow cylinder within which the, elemerit 2 isreciprocably mounted. Element 2.00mprises a pistoniportion 4- anda rod portion 5 and obviouslyyif any dampening. action is to be attained, there must be. resistance to. relative movement' of the-elements I and 2' andpreferablysuch resistance should varyinaccordance with the direction and the extentofrelative movement of said elements.

One manner of :achievingsuch aforesaid resi'stance and variable resistance to-relative movement of the elements! and 2' ist'o make thepiston portion 4 of such form that it will expand and contract to vary the friction betvveenit and the element l in response to opposite relative move ments thereof: In the embodiment of the invention illustrated in Figs; 1 and 2, the piston portion of the element 2* comprises spaced heads 6 and I, the-formerofwhich is immovably connected to the rod5 in any suitable manner as by a key 8 disposed in key-ways in theheadl and in the rod and lock nuts 9 in threaded engagement with the end of the-rod and the latter of which is movably connected to the rod 5 in such a manner that it will simultaneously rotate and move longitudinally therealong; Such latter connection will be presently described in detail.

Disposed between the heads 6 and I is a helical member H} having its opposite ends fastened as by screws H Fig, 2; to the respective heads. Said member [0 is preferably in the form of a coil spring wound from" rectangular cr-oss section wire and is of diameter such that it will snugly fit intothe element I.

The aforesaid movable connection between the head l 'and rod 5 comprises a pair of slots [2 in head I in each of Whicha ball I3 is movable. Each ball- I3 is fitted into a recess inthe rod and projects therefrom into theslot t2. Slots [2 are inclined relative to theaxis' of the rod and therefore any longitudinal movement of the head 1 relative to the rod 5 and head 6 will simultaneously effect rotation thereof relative to said rod and said head.

Threaded on torod 5 are look nuts l4 against which one end of a spring l5bears. The other end of the spring 15' bearsagainst head I and thus normally tends to urge the head 1 toward head 8. Thus; when thepiston portion 4 is inserted into the element I, the spring IE will be operative to move the head I downwardly, as viewed in Fig. 1, and to rotate the same clockwise as viewed in Fig. 2, both of which movements will increase the diameter of the helical member In and thereby force the outer surface thereof into engagement with the inner wall of element I. As is well known a helical member increases in diameter when axially compressed. To provide a still further increase in diameter the ends of a helical member may be rotated relative to one another to uncoil r unwind the same. In certain forms of my invention I utilize both of these expedients to accomplish variation in the diameter of helical member III and thus a variation in the contact pressure between member II] and the inner wall of element I.

The contact pressure between member I0 and element I can readily be varied simply by adjusting the nuts I4 along the rod 5 or by substituting a weaker or stronger spring I5 or by substituting a new head I having slots I2 therein inclined more or less than shown. In order that the contact pressure so effected will result in a substantial friction to effectively resist relative movement of the elements I and 2, helical member I 0 is preferably coated with a powdered metal which has a suitable coelficient of friction with the metal from which element I is made.

With the elements I and 2 in a static position, as illustrated in Fig. 1, the helical member I0 will be in frictional engagement with the inner wall of the element I. Now, if the vehicle parts or other parts with which the dampening device is associated are moved toward one another, such movement through the aforesaid frictional contact will effect relative movement of head 5 away from head I and because rod 5 is fixed against rotation, the head I will, by reason of the slot and ball connection, be caused to rotate in a counter-clockwise direction asviewed in Fig. 2, thereby in efiectwinding up the helical member ID. Both the longitudinal movement and the relative rotation of the heads 6 and I will effect a reduction in the diameter of member IIJ away from the inner wall of the element I. Such reduction in diameter will effect a reduction in the resistance to relative movement of the elements I and 2. In this way the resistance to movement of the elements I and 2 toward one another will decrease as such relative movement continues.

As soon as the vehicle parts or other parts commence movement away from one another, the friction of member III with element I will cause relative movement of the heads 6 and I toward one another, thereby compressing member It and at the same time eifecting rotation of head I in a clockwise direction, as viewed in Fig. 2, thereby unwinding or uncoiling the member I ll. Both of such actions forces the helical member Iii into progressively firmer contact with element I as such relative movement continues.- ;-Such gradual increase in resistance to relative movement of elements I and 2 effectively dampens the relative movement of the parts with which the dampening device is associated. Thus, if the device is connected to the axle and frame of an automobile, the wheels thereof can relatively freely pass over any irregularities in the road without lifting the frame along with it, but on the return movement of the wheels such dampening is of greater effect and quickly stops any tendency of the frame to continue to bounce up and down a number of time-s as would be the case if no dampening device were employed.

The device illustrated in Fig. 3 is substantia y the same as that of Figs. 1 and 2 and insofar as they are the same, like reference numerals have been usedto designate like parts. The only difference between Figs. 1 and 3 is that in Fig. 3 there is provided a friction sleeve I6 around the helical member I Ii. Said sleeve is slit longitudinally thereof as at H, so as to render the same readily expansible and contractible in response to expansion and contraction of the helical member III. Said sleeve can be made from friction material such as brake lining or it can be made of metal coated with a powdered material or pro vided with any suitable friction material coating. In order to hold said sleeve in proper position longitudinally of the head I, one end thereof is provided with an inturned flange 2'I which is fitted into a space between the end of helical member I I1. and a flange portion 28 of the head I. Inasmuch as the operation of this modified form is the same as that of Fig. 1, such will not now be repeated except to indicate that the sleeve I6 is of resilient construction and normally tends to collapse in diameter so that it is not necessary to fasten the same to member II].

The form of invention illustrated in Figs. 4 and 5 includes a two-part upper head structure in place of the head I shown in Fig. 1; that is, an outer section I8 to which one end of member ID is secure-d, and an inner section I9 which is longitudinally slidable relative to rod 5 and to outer section I 8. Said innersection I9 is connected to rod 5 through a spiral gear which is arranged so that said section will, when moved longitudinally of rod 5, simultaneously rotate. There is provided a longitudinally slidable ser-- rated connection 2 I between said sections These serrations may be parallel to the axis of rod 5 so that rotation of the outer section I8 will be the same as that of inner section I9, or if desired, such serrations may be inclined in the same or in an opposite direction from the inclination of the gear teeth whereby the total rotation of the outer section will be the sum of or the difference of the rotations of each section.

The spring 15 which bears against the inner section I9 tends to force said section downwardly and clockwise, as viewed in Figs. 4 and 5 respectively, thereby efi'ecting rotation of outer section I8 in a clockwise direction, as viewed in Fig. 5. Such rotation of the outer section I8 is effective to unwind member ID and thus expand sleeve I6 into frictional engagement with element I. In

I this modified form a spring 22 which bears against an inturned collar portion of sleeve I6 holds the sleeve in proper longitudinal relation to the outer section I8. As in the previously described forms, the form illustrated in Figs. 4 and 5 employs a spring I5 which, through a movable head, normally holds the sleeve IS in a frictional engagement with element I and in which opposite relative movements of elements I and 2 effect an increase or a decrease in the resistance to movement of said elements. I

From the drawing it will be evident that the dampening action can be varied in many ways, as for example, by changing the pitch and/or the wire size and shape of wire cross section of member III, by changing the pitch or inclination of the slots or gear teeth,'by varying the compression of spring I5 or by varying the coefficient of friction between the elements by substituting different metals therefor. Furthermore, it is contemplated that the heads might be reversed; that is, the lower head 6 may be made movable relative to the rod and the upper head I made immova umna? able relative to the-rode Likewisethe dampening action can obviously be reversed from that-shown, as-Ior' example by simply reversing the inclination of the slots or gear teeth. Also'itmay. be desirable in certaininstances to mount both heads so astobe movable on the rod: in which case the rotation of each may be in the same: direction. or in opposite directions: as desired.

One desirable feature of my invention. is: that the'ends of the helical member. li=berotated relatime to one another and. while .I have: shown in all forms of my invention: a spring pressing longi'tudinally against a. head: engagedi in. a. threadlilcelmanner' with a rod, such manner-of. accomplishing:relative'rotation; is to be considered: as merely typical. Also, while; my. invention 'may have particular utility as a shock absorber; in automobilesaor. otherxvehicles, it can be used with little or no modification as a door check or the like. r

Typical. examples, oiweys. other than those shown in Figs. 1-5 inclusive oflaccornplishing unwinding of member Hi to attain the desired initial static frictioncondition between member l0 and elemental or between sleeveifirand element: l are shnwninrFigs. 6 and 'I and inFig. 8. In theform ofrFigs. 6 and 7, one end of member In is connected to one end of a spiral spring 23 and the other end of spring 23 is connected to the rod in such manner that the uncoiling tendency of spring 23 tends to uncoil or unwind helical member [0 to thus urge the latter into frictional engagement with element l. The lower end of rod 5 may, of course, be fitted with a head as shown in Fig. 1. With an initial static friction so effected, it will be evident that opposite relative movements of elements I and 2 will effect axial lenghtening or shortening of member to thereby decrease or increase respectively the diameter thereof and thus vary the snubbing action between elements I and 2 as previously described.

In the form of invention illustrated in Fig. 8, the upper end of member In is fitted into one end of a transverse recess through a head 24 non-rotatably connected to rod 5. Within such recess is a spring 25 and an adjustable plug 26 threaded thereinto from its other end to urge spring 25 into engagement with the end of member Ill and thereby tend to expel the same from the recess. The effect of such force exerted by spring 25 on member Ill is to tend to unwind the same into firm engagement with element I. The lower end of member 10 is, of course, connected to a head 6, as shown in Fig. 1. It is to be noted that head 24 may or may not be fixed longitudinally of rod 5, as desired. If it is so fixed, then the relative movement of eyes 3 away from one another effects crowding of the coils of member ID toward head 6 to increase the resistance to such relative movement. On the other hand, movement of eyes 3 toward one another efiects a crowding of the coils of member l0 toward head 24 to increase the resistance to such relative movement. Thus, with such an arrangement, equal dampening occurs in both directions of relative movement of elements I and 2. If head 24 is mounted so as to be movable longitudinally of rod 5, then the action of the shock absorber is the same as that of Fig. 1 to produce a greater dampening efiect in one direction than in the other direction.

Itis to be understood, of course, that while for illustrative purposes I have shown my device in conjunction with a shock absorber of the direct acting type, it may be used with equal facility in a shock absorber of the link and lever type or inother. similar'types of shock absorbers. Inany event, the ultimate result which is desired is the dampening of movementsof relatively movable elements.

thermodesor applying the principle; of. .the invention may. be employed, change being made as regards. the details described. provided the features. stated in any of the following claims. or the equivalent of suchbe employed.

I therefore particularly point. out and dis.- tinctlyclaim as my invention:

1. A shoclc absorber element comprising a rod, spaced heads on said rod rotatable relativeto one another, a member connected to said heads expandible in response to relative rotation of'said heads'inone direction, and means normally tending to-rotatesaid heads relative to one another in said direction.

2'. A shockabsorber element comprisinga rod,

spacedheads on said rod rotatable relative to one another, a member connected to said' heads expandible in response to relative rotation: of said heads in: one direction, and means normally tending to rotate. said heads relative to one another in said direction, said means including. a spring bearing on one of" said heads and on said rod.

A shock absorber element comprising arod, spaced heads on said rod rotatable relative to one another, and a member connected to said heads expandible in response to relative rotation of said heads in one direction, one of said heads and said rod including interengaged portions comprising a slot inclined relative to the axis of said rod and a projection movable in such slot.

4.. A shock absorber element comprising a rod, spaced heads on said rod rotatable relative to one another, and a member connected to said heads expandiblc in response to relative rotation of said heads in one direction, one of said heads and said rod including interengaged portions comprising a slot in said head inclined relative to the axis of said rod and a ball carried by said rod movable in such slot.

5. A shock absorber element comprising a rod, spaced heads on said rod rotatable relative to one another, and an expandible member connected to said heads, said member being expandible in response to rotation of said heads relative to one another in one direction, one of said heads comprising inner and outer sections connected to one another, to said rod, and to said member in such manner that longitudinal movement of one of said sections relative to said rod is translated into rotation of that section which is connected to said member.

6. A shock absorber element comprising a rod, spaced heads on said rod rotatable relative to one another, an expandible member connected to said heads, said member being expandible in response to rotation of said heads relative to one another in one direction. one of said heads comprising inner and outer sections connected to one another, to said rod, and to said member in such manner that longitudinal movement of one of said sections relative to said rod is translated into rotation of that section which is connected to said member, and spring means bearing against said rod and one of said sections normally tending to effect such rotation.

7. In a shock absorber or the like, the cornbination of irictionally engaged elements reciprocable relative to one another, one of said elements comprising a helical member, and means associated with said member operable to wind and unwind said member in response to opposite reciprocatory movements of said elements to thus vary the friction between said elements.

8. In a shock absorber or the like, the combination of a cylinder, a helical member in said cylinder in frictional engagement therewith, said cylinder and member being reciprocable relative to one another, and means connected to said member operable to Wind and unwind the same in response to opposite reciprocatory movements of said cylinder and member to thus vary the friction between them.

9. A shock absorber element comprising a rod, relatively movable spaced heads on said rod, a helical member having its opposite ends connected to said heads, and means associated with at least one of said heads operable to wind and unwind said member in response to movement of said heads relative to one another in opposite directions.

10. A shock absorber element comprising a rod, relatively movable spaced heads on said rod, a helical member having its opposite ends connected to said heads, and means on said rod associated with at least one of said heads operable in response to movement of said heads relative to one another in opposite directions to effect rotation of said heads relative to one another in opposite directions, such relative rotation of said heads being efiective to wind and unwindsaid helical member. 11. In a shock absorber or the like, the combination of a cylinder, a piston reciprocable in said cylinder and in frictional engagement therewith, said piston comprising a rod having a fixed head and a movable head thereon with a helical member connected to said heads, and means associated with said rod and the movable head thereon for rotating said movable head in opposite directions in response to opposite reciprocatory movements of said cylinder and piston to thus expand and contract said helical member. to vary such friction between said piston and cylinder.

PETER B. OBERSTADT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 5 Number Name Date 2,136,908 Pierce Nov. 18, 19 38 2,212,759 Tea Aug. 2'7, 1940 

